This invention relates to a surgical instrument for sterilizing a patient, and especially to an instrument adapted to cut and occlude the Fallopian tubes, or oviducts, of a female patient.
Much misery is caused by unwanted pregnancy. It presents the unpalatable alternatives of abortion with its emotional turmoil and social cost or, if the parent(s) are unwilling to terminate the pregnancy for religious or other reasons, the imposition of an unexpected child. The life of the child and its parents can be ruined, with the child suffering from a lack of love and support and the relationship between its parents coming under strain due to emotional and financial problems. These problems can be all the worse if the child is physically or mentally handicapped.
There are also medical reasons for avoiding unwanted pregnancy. The parents""genetic makeup may predispose a child to be physically or mentally handicapped, or the mother may harbour infection such as HIV that might be passed on to the child. The parent(s) may be mentally or physically unable to look after a child, or the mother may be so ill that continuation or even termination of a pregnancy presents a serious risk to her.
For all of these reasons, reliable birth control or family planning is one of the major objectives of medical science. A large part of this effort relates to sterilization, which is now the most commonly-used method of family planning in the world. In 1990, for example, more than 190 million married women of reproductive age relied on sterilization of themselves or their partners for contraception. This represents 22% of married women of reproductive age in developing countries and 11% in developed countries. Indeed, in the US, sterilization has become the most commonly used method of contraception among married couples. Sterilization is intended to be permanent: reversal surgery is available, but it can be difficult and can never guarantee to restore fertility.
In the case of a female, sterilization generally involves occluding and optionally also cutting the Fallopian tubes, or oviducts, that convey ova from the ovaries to the cavity of the uterus. The term oviducts will be used hereinafter for convenience. Briefly, the oviducts are situated in the free margin of the broad ligament that extends outwardly in a layered web-like manner from the sides of the uterus. The part of the broad ligament that supports the oviducts is known as the mesosalpinx. The layers of the broad ligament also embrace the two round ligaments that extend forwardly, outwardly and downwardly from the uterus.
There are several sterilization techniques involving occlusion of the oviducts, notably:
(i) Ligation with partial salpingectomy, in which the oviducts are tied with suture material and cut, most commonly by tying off a small loop of the oviduct and then cutting through the loop. This procedure is performed through an abdominal incision and so is most often used when sterilization procedures are performed postpartum or if laparoscopic surgery is not possible because of obesity or inaccessibility, for example due to pelvic adhesions.
(ii) Coagulation or cautery, in which electrical current is used to block or divide the oviducts. This procedure is effective, but brings a risk of thermal injury to nearby tissues such as so-called bowel burn, as discussed by Thompson et al in Obstetrics and Gynaecology May 1973, Vol. 41, No. 5, at page 669 et seq.
(iii) The application of a silicone or Silastic band such as a Falope ring in which, using a special applicator, the surgeon forms a loop in the oviduct and stretches a small silicone ring to slip it over the loop. The ring thus compresses and occludes the oviduct at the neck of the loop, strangling the portion of oviduct that forms the loop. The procedure is discussed at length by Levinson et al in Obstetrics and Gynaecology October 1976, Vol. 48, No. 4, at page 494 et seq., and by Yoon et al in The Journal of Reproductive Medicine Jan. 15, 1977, Vol. 127, No. 2 at page 109 et seq., in the American Journal of Obstetrics and Gynaecology August 1979, Vol. 23, No. 2 at page 76 et seq., and in The Journal of Reproductive Medicine August 1979, Vol. 23, No. 2 at page 76 et seq.
(iv) The application of a clip to the isthmic part of the oviduct to compress and thus occlude the oviduct, most notably the Hulka-Clemens or Hulka spring clip most commonly used in the US and the Filshie clip most commonly used in Europe. Initial experience of the Hulka clip is discussed by Hulka et al in the American Journal of Obstetrics and Gynaecology, Jul. 1, 1973, Vol. 116, No. 5 at page 715 et seq. Similar experience of the Filshie clip is discussed by Filshie et al in the British Journal of Obstetrics and Gynaecology June 1981, Vol. 88, pp. 655-662. There are other types of occlusive clip, such as the recently-introduced Cambridge clip.
Apart from ligation with partial salpingectomy, the above procedures are apt to be performed laparoscopically. Laparoscopic female sterilization is popular because of its short recovery time and relatively low complication rate.
As female sterilization is invariably performed upon those for whom pregnancy is deemed to be undesirable or unsafe, it follows that the probable consequence of a failed sterilizationxe2x80x94an unexpected pregnancyxe2x80x94is all the more damaging. Failed sterilization also involves an increased risk of ectopic pregnancy, which presents a very direct threat to the patient""s health: as many as one third of sterilization failures involve ectopic pregnancy. Unsurprisingly, therefore, failed sterilization is one of the major reasons for law suits against gynaecologists and obstetricians, in some countries accounting for one third of all such cases.
The prospect of damages and legal costs coupled with the increasingly hostile climate of litigation for medical negligence adds to the stress of the physician""s life and escalates the cost of medical negligence insurance. Nor should the professional impact of a medical negligence claim be forgotten: an accusation of negligence based upon a failed sterilization can be as damaging for the physician""s professional career as it is for the lives of those most directly affected by an unwanted pregnancy.
Sterilization can fail for various reasons, but where an occlusive device is employed, failure can usually be attributed to improper application of the occlusive device. A clip should be applied so that it completely compresses and occludes the oviduct, for which purpose the clip should be placed on the distal isthmus end of the oviduct (3 cm from the cornual end of the uterus) at precisely 90xc2x0 to the longitudinal axis of the oviduct, with one side of the oviduct lying against the hinge of the clip and the clip embracing part of the mesosalpinx on the other side of the oviduct. If these objectives are not fully met, the clip might not properly occlude the oviduct. Analogous problems are encountered with Falope rings, as explained in the abovementioned 1979 paper by Yoon et al in The Journal of Reproductive Medicine. It is even possible for the clip or ring to be applied to the wrong structure entirely, for example to the round ligament that can quite easily be confused with the oviduct during laparoscopic procedures.
Both clips and rings can fail if the oviducts are thicker than normal for whatever reason. Clips may be unable to cross the full thickness of the oviduct, and the loop of oviduct formed by a ring applicator may be severed by the force used to pull the loop into the applicator. Rings also fail sometimes because the applicator does not form a proper loop in the oviduct, especially when the loop is too small. In that instance, any stretching movement of the oviduct will cause the ring to slip.
Not all failed sterilizations are the physician""s fault. Clips or rings can slip from an oviduct even if they are properly applied, although this is a difficult situation to verify as a misplaced clip or ring could, of course, merely indicate failure by the physician properly to apply the clip or ring to the oviduct. The benefit of any such doubt is not often exercised in the physician""s favour, bearing in mind that the mere existence of doubt can be sufficient grounds for a successful negligence claim or at least lead to an expensive settlement. It is also known that a clip or ring can migrate from the oviduct when the crushed tissue at the site of its application undergoes necrosis and the oviduct divides into stumps, the clip or ring then possibly either lodging in nearby tissue or, in very rare cases, being expelled from the body through the vagina or rectum. It is unlikely that a patient would regain fertility in the event of such migration but it clearly presents a risk of complications such as infection and tissue damage.
Such is the risk of litigation that some gynaecologists and obstetricians make video tapes or still pictures of each and every sterilization procedure that they perform, so that if ever challenged, they have at least some evidence to confirm that the procedure was done properly. These images are kept in the patient""s records for future reference but must be kept for several years, at least until the patient""s reproductive capacity has ended with age.
It is against this background that the present invention has been made.
The invention resides in a laparoscopic sterilization instrument comprising excision means for excising a portion of a patient""s oviduct and a receptacle for holding the excised oviduct portion until the instrument has been withdrawn from the patient""s abdomen. The excised oviduct portion constitutes a full circumference biopsy that can be examined to confirm proper performance of the sterilization procedure, for the protection of patient and physician alike. The invention also resides in methods for use of the instrument.
In the preferred embodiment to be described, the instrument includes first and second elongate parts defining longitudinal axes and distal and proximal ends, the parts being attached to each other for relative movement parallel to their longitudinal axes to operate the excision means. More specifically, in that embodiment, the first part is a rod and the second part is a sleeve within which the rod can move, the rod suitably moving by sliding within the sleeve.
The excision means of the instrument preferably comprises at least one excision blade on at least one of the parts and means associated with the receptacle for gripping the oviduct and moving the gripped oviduct across the excision blade during said relative movement between the parts. Conveniently, the movement of the gripped oviduct across the excision blade takes place in a proximal direction. Where the first part is a sleeve, as is preferred, the excision blade is suitably associated with the distal end of the sleeve to cut the gripped oviduct during proximal movement of the rod. For example, the excision blade can be defined by at least one sharp-edged cut-out in the distal end of the sleeve.
Advantageously, the instrument further includes means attached to one of the parts being co-operable with the other of the parts to limit relative movement of the parts. Movement can be limited along (or in parallel to) and about the longitudinal axes of the parts.
As sterilization usually involves the application of an occlusive device such as a clip or ring, the instrument preferably further includes application means for applying an occlusive device to the oviduct. Where the occlusive device is a ring, that ring is advantageously held on a first part of the instrument and the application means operates by relative movement of the second part of the instrument to move the ring off the first part and onto the oviduct. Where these parts are a rod and a sleeve as aforesaid, a shoulder or ramp on the distal end of the sleeve suitably abuts the ring to force the ring off the distal end of the rod during proximal movement of the rod relative to the sleeve.
It is greatly preferred that the instrument is operable by a physician to work the excision means and the application means in a single action. In that case, it is also preferred that the application means operates before the excision means during that action. This affords the physician every opportunity to check and if necessary repeat any aspect of the procedure before the oviduct is cut.
Efficiently to receive the oviduct, the receptacle is preferably disposed transversely with respect to the longitudinal axis of the instrument. In preferred embodiments, the receptacle is defined between co-operating formations in opposed jaws provided at the distal end of the instrument. These formations are preferably troughs extending across the jaws, that co-operate to define the receptacle when the jaws are closed.
For reliable grip on the oviduct during the procedure, barb or tooth means are preferably associated with at least one trough, being adapted to resist removal of the oviduct from the receptacle or the trough.
For reliability in forming a loop of the oviduct ready for application of an occlusive device and then excision, the trough is separated from the distal extremity of the jaw. The separation is preferably at least 1 cm. To obtain a usefully large biopsy sample of the oviduct, the trough is preferably at least 5 mm long.
To achieve easy separation of the oviduct from the supporting mesosalpinx, blade means may be associated with the jaws. Such blade means are disposed distally with respect to the receptacle, and are operable on closure of the jaws to cut into or through the mesosalpinx. The blade means comprises a blade on at least one jaw, the blade being disposed transversely with respect to the longitudinal axis of the instrument, and means on the other jaw co-operable with the blade.
Conveniently, the jaws of the instrument can be opened by an actuating link operable from the proximal end of the instrument. The jaws can be opened by distal movement of this actuating link and hence can be closed by proximal movement of the actuating link. In a particularly elegant arrangement, continued proximal movement of the actuating link operates the excision means to excise the portion of oviduct held by the receptacle in the jaws.
To keep the jaws closed until they are required to be open, the jaws are preferably biased shut by spring means. The spring means suitably biases the actuating link proximally.
For ease of operation, manipulation means of the instrument preferably include means on the actuating link adapted for co-operation with the operator""s thumb and means on an opposed part of the instrument adapted for co-operation with fingers of the operator""s same hand. These manipulation means are suitably a ring on the actuating link and a flange on the opposed part of the instrument.
Within the inventive concept, the invention may also be expressed as a laparoscopic sterilization instrument including application means for applying an occlusive device permanently to occlude a patient""s oviduct, and means for excising a full circumference biopsy of the oviduct during the sterilization procedure. This instrument is preferably adapted to form a loop in the oviduct, to apply the occlusive device to the neck of the loop, and to excise the biopsy from the portion of oviduct within the loop. It is further preferred that the instrument is adapted to leave free end sections of the portion of the loop that remains after excision of the biopsy. These features combine to facilitate a simple procedure that gives reliable results for the reproductive life of the patient.
The instrument as defined herein can be supplied in a sterile pack with an occlusive device already fitted. In that case, the instrument is suitably adapted for single use only.
The invention extends to an occlusive clip or ring for application to a patient""s oviduct during a sterilization procedure, wherein the clip or ring is a resilient disc defining a face, the disc being penetrated by at least one slit that extends almost entirely across the face of the disc to define a central opening flanked by wall portions of different thickness. The slit is preferably rectilinear and there can be first and second intersecting slits, which are preferably symmetrically intersecting and orthogonally disposed to define a cross-shaped central opening. The invention also encompasses a clip or ring for application to a patient""s oviduct during a sterilization procedure, the clip or ring including means for cutting the oviduct and means for occluding the oviduct.